A single in-line memory module (SIMM) or a single in-line package (SIP) comprises a generally planar substrate having an array of electrical components disposed thereon. The components on the substrate may comprise "intelligent" electrical components, such as integrated circuit chips. These components are appropriately connected to one another by circuitry disposed on the substrate. The circuitry extends to discrete conductive regions that are equally spaced along one edge of the planar substrate.
A memory module or single in-line package is removably engageable with a socket that typically is mounted to a circuit board, panel or the like. More particularly, the prior art socket comprises a slot dimensioned to engage the edge of the substrate having the discrete conductive regions. The socket further includes a plurality of terminals extending at least partly into the slot to contact the discrete conductive edge regions of the memory module or single in-line circuit package.
Many prior art sockets for memory modules or single in-line packages are designed for the simple pushing or pulling of the module or package into or out of the slot generally along the plane of the substrate. The movement of the single in-line package into the slot causes the terminals of the prior art socket to deflect, and the resiliency of the deflected terminals causes contact forces to be exerted against the conductive regions on the edge of the single in-line package. These contact forces are intended to insure consistent high quality electrical connection to the conductive regions on the edge of the single in-line package. Although prior art sockets of this type may perform well in many environments, it is difficult to design such a push-pull socket that will achieve a low insertion force for the single in-line package, and that also will achieve high normal contact forces between the terminals of the socket and the conductive regions on the edge of the package. Insertion or withdrawal forces that are too high can damage either the package or the terminals of the socket to which the circuit package is mateable. Conversely, a socket designed to facilitate the pushing of the circuit package into the socket or the pulling of the circuit package out of the socket generally will achieve lower normal contact forces between the terminals of the socket and the conductive regions on the edge of the circuit package. These lower contact forces make it difficult to assure that the socket will perform well during all ranges of vibration, shock or temperature to which the socket may be presented. In this regard, it should be noted that extreme ranges of vibration, shock and temperature often are encountered in automotive vehicles and aircraft and in some office machines or computers.
To overcome the inherent problems with push-pull sockets for single in-line packages or memory modules, sockets have recently been developed which enable low insertion and withdrawal forces and that achieve a high quality electrical connection. More particularly, the fairly recent prior art includes sockets that enable a single in-line package to be inserted into the slot of the socket at a first angle with negligible insertion force and that then enable the package to be rotated into a second angular alignment at which a high contact force is achieved. These prior art sockets include means for releasably locking the single in-line package or memory module in an angular alignment corresponding to optimum contact forces. Additionally, these prior art sockets may include means for preventing the single in-line package or memory module from being vibrated or pulled out of the completely inserted position in the socket. Examples of very desirable prior art sockets of this type are shown in U.S. Pat. No. 4,575,172 which issued Walse, et al. on Mar. 11, 1986 and U.S. Pat. No. 4,713,013 which issued to Regnier, et al. on Dec. 15, 1987. These two prior art patents are assigned to the assignee of the subject invention, and the disclosures are incorporated herein by reference.
Recent generations of single in-line packages include substrates formed from ceramic materials. Many of the substrates are somewhat fragile and can be damaged if subjected to direct force or extreme vibration. The forces that are likely to damage such a ceramic substrate could be those encountered during insertion of the single in-line package into a socket, removal of the single in-line package from a socket or a direct inadvertent contact with a fully seated package. In particular, some small single in-line packages having fragile substrates may be subject to damage in response to forces generated against the ramped surfaces of the latches on some prior art sockets. The memory module or single in-line packages usually are safely removed from the prior art socket by merely rotating the latches away from one another such that the biasing forces of the terminals in the socket will cause the memory module or package to effectively pop out of its fully seated alignment into an alignment where it is free of the latches. Unfortunately, however, many technicians will not follow this preferred removal feature. Thus, a technician may manually exert rotational forces on the memory module or single in-line package against the locking forces of the latches. Additionally, technicians often will attempt to merely pull the memory module or package out of the socket in a direction aligned with the plane of the substrate. These improper withdrawal forces can easily damage the fragile substrate employed on many currently manufactured single in-line packages.
Even if a memory module is properly inserted and withdrawn from its socket there are many environments where damage can be caused by inadvertent contact. For example, sophisticated electronic circuitry is now commonplace in most automotive vehicles. Many portions of this circuitry, such as an engine management system, require single in-line memory modules or single in-line packages to control or coordinate operations. These modules and packages often are disposed at locations where they may inadvertently be contacted by a technician performing work on a nearby part of the vehicle. Additionally, the memory modules and single in-line packages employed in the automotive environment are subjected almost continuously to extreme conditions of vibration, shock and temperature change. These environmental conditions and the likelihood of direct contact create the potential for damage to the fragile substrate incorporated into many such memory modules and single in-line packages.
In view of the above, it is an object of the subject invention to provide a socket assembly for single in-line packages of electronic circuitry.
It is another object of the subject invention to provide a socket assembly for avoiding damage to a single in-line package mated therewith.
It is an additional object of the subject invention to provide a single in-line package socket assembly that prevents direct force on the substrate of the package during mating and unmating.
Still a further object of the subject invention is to provide a socket assembly for a single in-line package that enables the package to be substantially completely enveloped and protected in its mated condition.